**6. Marine pollution and the impact of industrialization on cetaceans – A possible cause?**

Rapid population growth and industrialization have characterized urban development. However, the rate of population growth is far higher than the rate of waste and wastewater infrastructure planning and development [1, 66]. This phenomenon has led to ever increasing pressure on natural resources and the creation of massive volumes of waste and waste water [67]. Marine pollution had been defined as deleterious effects resulting, either directly or indirectly, from the introduction of substances or energy by humans to the marine environment [66]. High levels of marine pollution especially along urban areas, pose a serious threat to the health of humans, as well as marine mammals. Although numbers of cetaceans have markedly improved over the past few years as a result of conservation efforts, the quality of the habitat in and near bay areas are critical, because these areas are used by these marine mammals for feeding, mating and calving [1]. Waste entering the marine environment had been categorized into the following groups of activities [68]:


Waste from ships, oil spills and the discharge of ballast water, as well as other waste.

Cutaneous Lesions in Cetaceans: An Indicator of Ecosystem Status? 139

*Staphylococcus aureus, Pseudomonas putrefaciens, Aeromonas hydrophila* and *Legionellae pneumophila.* Cases of skin infections were found to be caused by opportunistic spp. of *Aeromonas, Mycobacterium, Staphylococcus* and *Vibrio,* after swimming in contaminated

Sewage pollution may also influence the diversity of potential fungal pathogens that are known to infect humans and animals. Keratinophilic microbes occur in high numbers in sewage sludge since it contains high concentrations of keratin remnants [16]. These fungi, including the so-called dermatophytes are known as causative agents of a wide variety of cutaneous and subcutaneous mycoses. Awad and Kraume [23] found the following fungal species, retained in the following genera, in aerobic and anoxic sludge from wastewater plants in Berlin, Germany: *Chrysosporium, Microsporum, Trichophyton, Acremonium, Alternaria, Aspergillus, Candida, Chaetomium, Cladosporium, Fusarium, Geotrichum, Gliocladium, Gymnoascus, Mucor, Paecilomyces, Penicillium, Scopulariopsis, Sporothrix, Trichoderma* and *Verticillium.* It has been stated that the release of these fungi into the environment via

Heavy metals are metallic chemical elements with a relatively high density and are also known as 'toxic metals'. This group includes elements such as copper (Cu), zinc (Zn), lead (Pb), mercury (Hg), nickel (Ni), cobalt (Co), arsenic (As), thallium (Tl) and chromium (Cr). These metals are common components of the earth's crust and occur naturally in ecosystems at different concentrations. However, the bio-available concentrations of these elements have increased significantly over time since the dawn of the Industrial Revolution. The resulting bio-accumulation of these metals has reached critical levels in many ecosystems. These elements enter the water supply through industrial and consumer waste, or acidic rain that in turn causes chemical reactions in soil releasing the metals into streams, rivers and ground water. Additional sources include waste from chemical, electro-plating, tanning, smelting and especially the mining industry [70]. Previously, the lead added to motor fuels as an anti-knock agent was released on large scale into the atmosphere in exhaust fumes with a substantial proportion settling on road surfaces. Run-off water from these surfaces therefore contained high levels of lead. Urbanized and heavy industrialized

Living organisms require small amounts of certain heavy metals or trace elements for normal metabolic processes, in the form of co-factors in enzymes. Some heavy metals such as Cd, As, Pb and Hg pose the biggest threat to the health of humans and animals, and daily intake of these metals are toxic and often fatal. Long-term exposure of humans to As in drinking water for example, had been reported to cause increased risk to skin and other types of cancer, as well as other skin lesions including hyperkeratosis and pigmentation anomalies. Similarly, Cd exposure is associated with kidney damage and increased incidence of bone fractures [70]. Marine mammals often occupy the top levels of marine food chains, and therefore, heavy metals accumulate in these animals [72]. In water, heavy

activated sludge, presents an indisputable health risk [11, 23].

areas are consequently the foci of heavy metal pollution [71].

recreational waters.

**6.2. Heavy metals** 

